For Microsoft and Borland C++ builds, this tells Boost.Regex that
it should link to the dll build of the Boost.Regex. By default boost.regex
will link to its static library build, even if the dynamic C runtime
library is in use.

BOOST_REGEX_NO_LIB

For Microsoft and Borland C++ builds, this tells Boost.Regex that
it should not automatically select the library to link to.